— Exhibit –
— Exhibit —
Click the Exhibit button.
In the exhibit, the routers in the network have a default PIM sparse mode configuration. R2 shows
that R1 is the RPF next hop for the source, and R3 is the RPF next hop for the RP. Host1 is
currently receiving multicast traffic for group 231.1.1.1. Host2 has come online and is attempting to
join group 232.1.1.1. R2 has just received an IGMP message with the source and group
addresses.
Which step happens next so that Host2 can join the multicast group?
A.
R2 sends a PIM join upstream towards R3 to join the shared tree.
B.
R2 sends a PIM join upstream towards R3 to join the source tree.
C.
R2 sends a PIM join upstream towards R1 to join the shared tree.
D.
R2 sends a PIM join upstream towards R1 to join the source tree.
shouldn’t it B ? If not i don’t really understand the RP job.
It is not clear if the multicast source has already send a PIM register message.
the RP has state (S,G) and also R1
R2 and R3 has (*,G) state for the new group 232.1.1.1
Maybe the trickey part is the used SSM address 232/8 (source specific multicast)
This uses only a SPT tree is necessary.
In this question it is not clear if a IGMPv3 join is used.
So D could be the right answer. (because of the used 232/8 address which is SSM)
In the question:
R2 has just received an IGMP message with the source and group
addresses.
If the word “source” is an unicast address then it will be IGMPv3. (Receiver knows the source)
Else it is * which is any source. The multicast receiver does not know the source.
D is correct.
By the way, part of the new 80Q JNCIP-ENT JN0-647 dumps for your reference:
https://drive.google.com/open?id=0B-ob6L_QjGLpejBJUUI1X2NuU3M
Best Regards!